1. Field of the Invention
The present invention relates to an intervertebral artificial disc replacement, and more particularly to an intervertebral tensional artificial disc replacement which is implanted to replace a damaged disc between vertebrae.
2. Description of the Related Art
A disc is between vertebrae, the outside of the disc is protected by tough fiber, and a nucleus pulposus is present inside the disc.
The disc functions as a joint, and plays a very important role in reducing an impact applied to a spine by changing the position and form of the nucleus pulposus according to the movement of the spine. The nucleus pulposus consists mostly of moisture (water), and the disc loses its buffering function as humans grow old and the amount of moisture is gradually reduced. For this reason, backaches occur when excessive pressure is applied to the fiber, and if this state worsens, the fiber presses posterior nerve roots while being greatly stretched or ruptured, thereby causing pain in the pelvis, legs, etc. Then, a variety of side effects such as vertebral deformation occur while the gap between vertebrae is gradually narrowed or the vertebrae move down. Accordingly, when a surgical operation is performed to remove discs which are badly bent or damaged, it is basically necessary to take measures for maintaining the gap between vertebrae and preventing the vertebrae from being deformed or rocked.
Conventionally, spinal fusion is mainly performed to fix vertebrae using titanium screws or the like while maintaining the normal gap between the vertebrae. However, the conventional medical procedures may cause side effects such as backaches due to the fixed vertebrae.
Accordingly, artificial disc replacements (ADRs) have been recently developed and are being well received by patients. Artificial disc replacement is a surgical method for treating discs without fixing a vertebral body. Even after the surgical operation, the artificial disc replacement implanted by the surgical operation is similar to the disc of a human body in terms of mobility, flexibility, and safety of vertebral segments, and side effects such as backaches due to the conventional spinal fusion do not occur.
In connection with such a recent artificial disc replacement, the artificial disc replacement includes an upper fixed body, a lower fixed body, and an intermediate connection body which is inserted therebetween to connect the upper and lower fixed bodies. Since the upper fixed body moves depending on the movement of vertebrae in the state in which the upper fixed body is in contact with the intermediate connection body, there is a problem in that the intermediate connection body and the upper fixed body become worn due to friction when used for a long period, and foreign substances may be generated in a human body. In addition, since the upper fixed body and the intermediate connection body must be made of special materials in order to prevent the generation of foreign substances, high expense is incurred.